Transcript for America Issues New Warning to Iran About Nuclear Weapons

because america has issued a blunt, new warning tonight to iran about nuclear weapons. And abc's chief glow affairs correspondent martha raddatz is in the middle east to tell us what happened tonight and what it means. Martha? Reporter: Good evening, diane. Sharp words today about what this administration clearly sees as america's two greatest threats. Iran and syria. Secretary of state john kerry came out blasting today, hitting and warning more help for the rebels fighting assad could be coming. But then kerry turned to iran, saying time is running out for a peaceful solution to that nation's nuclear ambitions. Back home, vice president biden took a swing, too. Warning military options are not off the table. Big nations can't bluff. And presidents of the united states cannot and do not bluff and president barack obama is not bluffing. Reporter: Why the heat? Remember that red line that israel's prime minister netanyahu drew, warning that if the world didn't step in by spring or early summer, it would be too late to keep iran from developing a nuclear bomb. Secretary kerry arrives here in qatar soon to drive home that message. We will sit down with him tomorrow to talk about these world crisis.

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